Change in the acid-base status of an Appalachian mountain catchment following forest defoliation by the gypsy moth

• Published in: Water, air and soil pollution air and soil pollution, 1995-12, Vol.85 (2), p.535-540
• Main Authors: Webb, J.R, Cosby, B.J, Deviney, F.A. Jr, Eshleman, K.N, Galloway, J.N
• Format: Article
• Language: English
• Subjects: acid neutralizing capacity; acidification; acidity; Acids; Animal and plant ecology; Animal, plant and microbial ecology; anions; Biological and medical sciences; cations; deciduous forests; defoliation; Ecosystems; Environmental impact; Fresh water ecosystems; Fundamental and applied biological sciences. Psychology; Geochemistry; Hydrogen; hydrogen ions; infestation; Ions; Lymantria dispar; national parks; Nitrates; Q1; shenandoah national park; streams; sulfates; Sulfur compounds; Synecology; water quality; watersheds
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/bf00476884

Infestation by the gypsy moth (Lymantria dispar) can alter biogeochemical conditions in affected catchments. Stream-water concentration data obtained over the period of 1980-1993 for White Oak Run, a stream in Shenandoah National Park, Va., indicate that change in catchment acid-base status is associated with forest defoliation by the moth larva. Stream-water concentration changes following defoliation included increasing concentrations of strong-acid anions, base-cations, and hydrogen ion, as well as decreasing concentrations of acid-neutralization capacity (ANC) and sulfate. The largest change was in the concentration of nitrate; annual discharge-weighted mean concentrations increased from predefoliation levels consistently less than 5 mu eq/L to postdefoliation levels greater than 50 mu eq/L. An intensification of acidification was indicated by record-high hydrogen ion concentrations and record-low ANC concentrations. The long-term biogeochemical implications of the infestation are uncertain due to the nonlinearity of the observed responses and unknown patterns of recovery and recurrence.